Display system with an optical combiner

Abstract

An electronic device may include a display module that generates image light and an optical system that redirects the image light towards an eye box. The optical system may include an input coupler on a waveguide and collimating optics that collimate the image light between the image light exiting a display module and the image light reaching the input coupler. An optical combiner may combine image light from multiple display modules and output the light to one or more collimating lenses. The display modules, the optical combiner, and the collimating lenses may be attached to a chassis. A display module may have an array of microlens that overlaps an array of light-emitting diodes. The microlenses may have a different horizontal pitch and / or vertical pitch than the light-emitting diodes.

Description

Display System with an Optical CombinerThis application claims priority to U.S. Provisional Patent Application No.63 / 714,720, filed October 31, 2024, which is hereby incorporated by reference herein in its entirety.Background

[0001] This relates generally to optical systems and, more particularly, to optical systems for displays.

[0002] Electronic devices may include displays that present images to a user’s eyes. For example, devices such as virtual reality and augmented reality headsets may include displays with optical elements that allow users to view the displays.

[0003] It can be challenging to design devices such as these. If care is not taken, the components used in displaying content may be unsightly and bulky and may not exhibit desired levels of optical performance.Summary

[0004] A display system may include a first waveguide, a second waveguide, an optical combiner that is interposed between the first and second waveguides, a first catadioptric lens that is interposed between the first and second waveguides and that redirects first image light from the optical combiner to the first waveguide, a second catadioptric lens that is interposed between the first and second waveguides and that redirects second image light from the optical combiner to the second waveguide, and a plurality of display modules that provides the first image light and the second image light to the optical combiner.

[0005] An electronic device may include a housing, a first waveguide coupled to the housing, a second waveguide coupled to the housing, a first chassis, a second chassis that is attached to the first chassis and the housing, a first lens that is interposed between the first chassis and the second chassis, a second lens that is interposed between the first chassis and the second chassis, an optical combiner that is attached to the first chassis, and a plurality of display modules that is attached to the first chassis and that provide image light to the optical combiner. A first portion of the first lens may be adjacent to the first waveguide and a first portion of the second lens may be adjacent to the second waveguide.

[0006] A display system may include a first waveguide, a second waveguide, a first catadioptric lens that is interposed between the first and second waveguides and that redirects image light to the first waveguide, a second catadioptric lens that is interposed between the first and second waveguides and that redirects the image light to the second waveguide, and at least one display module that provides the image light to the first and second catadioptric lenses. The at least one display module may include an array of light-emitting diodes and an array of microlenses that overlaps the array of light-emitting diodes, the array of lightemitting diodes may have a first horizontal pitch and a first vertical pitch, and the array of microlenses may have a second horizontal pitch that is different than the first horizontal pitch and a second vertical pitch that is different than the first vertical pitch.Brief Description of the Drawings

[0007] FIG. l is a diagram of an illustrative system having a display in accordance with some embodiments.

[0008] FIG. 2 is a top view of an illustrative display system with multiple display modules, an optical combiner for the multiple display modules, a waveguide, and collimating optics in accordance with some embodiments.

[0009] FIG. 3 is a top view of an illustrative display system with a 5-surface catadioptric collimating lens in accordance with some embodiments.

[0010] FIG. 4 is a top view of an illustrative display system with a 4-surface catadioptric collimating lens in accordance with some embodiments.

[0011] FIG. 5 is a top view of an illustrative display system with a 5-surface catadioptric collimating lens that includes first and second lens elements with different refractive indices in accordance with some embodiments.

[0012] FIG. 6 is a top view of an illustrative display system with a 6-surface catadioptric collimating lens that includes first and second lens elements in accordance with some embodiments.

[0013] FIG. 7 is a top view of an illustrative display system with a 3-surface catadioptric collimating lens in accordance with some embodiments.

[0014] FIG. 8 is a top view of an illustrative display system with two waveguides, two collimating lenses, two optical combiners, and six display modules in accordance with some embodiments.

[0015] FIG. 9 is a top view of an illustrative display system with two waveguides, two collimating lenses, one optical combiner, and six display modules in accordance with some embodiments.

[0016] FIG. 10 is a top view of an illustrative display system with two waveguides, two collimating lenses, one optical combiner, and three display modules in accordance with some embodiments.

[0017] FIG. 11 A is a top view of an illustrative optical combiner with roughened surfaces and ink coatings for crosstalk mitigation in accordance with some embodiments.

[0018] FIG. 1 IB is a top view of an illustrative optical combiner with baffles for crosstalk mitigation in accordance with some embodiments.

[0019] FIG. 11C is a top view of an illustrative optical combiner with functional layers for crosstalk mitigation in accordance with some embodiments.

[0020] FIGS. 12A-12D are cross-sectional views of an illustrative projector module in accordance with some embodiments.

[0021] FIG. 13 is a cross-sectional view of an illustrative head-mounted device with the projector module of FIGS. 12A-12D mounted in a housing in accordance with some embodiments.

[0022] FIG. 14A is a top view of an illustrative display module with an array of lightemitting diodes in accordance with some embodiments.

[0023] FIG. 14B is a top view of the illustrative display module of FIG. 14A showing an array of microlenses that overlap the array of light-emitting diodes in accordance with some embodiments.Detailed Description

[0024] An illustrative system having a device with one or more near-eye display systems is shown in FIG. 1. System 10 may be a head-mounted device having one or more displays such as near-eye displays 14 (sometimes referred to as display systems 14 or near-eye display systems 14) mounted within support structure (housing) 20. Support structure 20 may have the shape of a pair of eyeglasses (e.g., supporting frames), may form a housing having a helmet shape, or may have other configurations to help in mounting and securing the components of near-eye displays 14 on the head or near the eye of a user. Near-eye displays 14 may include one or more display modules such as display modules 14A (see FIG. 2) andone or more optical systems such as optical systems 14B. Display modules 14A may be mounted in a support structure such as support structure 20. Each display module 14A (shown as part of control circuitry and additional components 13 in FIG. 1) may emit light 22 (image light) that is redirected towards a user’s eyes at eye box 24 using an associated one of optical systems 14B.

[0025] The operation of system 10 may be controlled using control circuitry and additional components 13. Control circuitry and additional components 13 may include control circuitry. The control circuitry may include storage and processing circuitry for controlling the operation of system 10. The control circuitry may include storage such as hard disk drive storage, nonvolatile memory (e.g., electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in the control circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, graphics processing units, application specific integrated circuits, and other integrated circuits. Software code (instructions) may be stored on storage in the control circuitry and run on processing circuitry in the circuitry to implement operations for system 10 (e.g., data gathering operations, operations involving the adjustment of components using control signals, image rendering operations to produce image content to be displayed for a user, etc.).

[0026] System 10 may include input-output circuitry such as input-output devices 12. Input-output devices 12 may be used to allow data to be received by system 10 from external equipment (e.g., a tethered computer, a portable device such as a handheld device or laptop computer, or other electrical equipment) and to allow a user to provide head-mounted device 10 with user input. Input-output devices 12 may also be used to gather information on the environment in which system 10 (e.g., head-mounted device 10) is operating. Output components in devices 12 may allow system 10 to provide a user with output and may be used to communicate with external electrical equipment. Input-output devices 12 may include sensors and other components (e.g., image sensors for gathering images of real-world objects that are digitally merged with virtual objects on a display in system 10, accelerometers, depth sensors, light sensors, haptic output devices, speakers, batteries, wireless communications circuits for communicating between system 10 and external electronic equipment, etc.).

[0027] Display modules 14A may include reflective displays (e.g., liquid crystal on silicon (LCOS) displays, digital-micromirror device (DMD) displays, or other spatial light modulators), emissive displays (e.g., micro-light-emitting diode (uLED) displays, organic light-emitting diode (OLED) displays, laser-based displays, etc.), or displays of other types. Light sources in display modules 14A may include uLEDs, OLEDs, LEDs, lasers, combinations of these, or any other desired light-emitting components.

[0028] Optical systems 14B may form lenses that allow a viewer (see, e.g., a viewer’s eyes at eye box 24) to view images on display(s) 14. There may be two optical systems 14B (e.g., for forming left and right lenses) associated with respective left and right eyes of the user. A single display 14 may produce images for both eyes or a pair of displays 14 may be used to display images. In configurations with multiple displays (e.g., left and right eye displays), the focal length and positions of the lenses formed by components in optical system 14B may be selected so that any gap present between the displays will not be visible to a user (e.g., so that the images of the left and right displays overlap or merge seamlessly).

[0029] If desired, optical system 14B may contain components (e.g., an optical combiner, etc.) to allow real -world image light from real -world images or objects 25 to be combined optically with virtual (computer-generated) images such as virtual images in image light 22. In this type of system, which is sometimes referred to as an augmented reality system, a user of system 10 may view both real -world content and computer-generated content that is overlaid on top of the real-world content. Camera-based augmented reality systems may also be used in device 10 (e.g., in an arrangement which a camera captures real -world images of object 25 and this content is digitally merged with virtual content at optical system 14B).

[0030] System 10 may, if desired, include wireless circuitry and / or other circuitry to support communications with a computer or other external equipment (e.g., a computer that supplies display 14 with image content). During operation, the control circuitry may supply image content to display 14. The content may be remotely received (e.g., from a computer or other content source coupled to system 10) and / or may be generated by control circuitry (e.g., text, other computer-generated content, etc.). The content that is supplied to display 14 by the control circuitry may be viewed by a viewer at eye box 24.

[0031] FIG. 2 is a top view of an illustrative display 14 that may be used in system 10 of FIG. 1. As shown in FIG. 2, near-eye display 14 may include one or more display modules such as display modules 14A-1, 14A-2, and 14A-3 and an optical system such as opticalsystem 14B. Optical system 14B may include optical elements such as one or more waveguides 26. Waveguide 26 may include one or more stacked substrates (e.g., stacked planar and / or curved layers sometimes referred to herein as waveguide substrates) of optically transparent material such as plastic, polymer, glass, etc.

[0032] If desired, waveguide 26 may also include one or more layers of holographic recording media (sometimes referred to herein as holographic media, grating media, or diffraction grating media) on which one or more diffractive gratings are recorded (e.g., holographic phase gratings, sometimes referred to herein as holograms). A holographic recording may be stored as an optical interference pattern (e.g., alternating regions of different indices of refraction) within a photosensitive optical material such as the holographic media. The optical interference pattern may create a holographic phase grating that, when illuminated with a given light source, diffracts light to create a three-dimensional reconstruction of the holographic recording. The holographic phase grating may be a non- switchable diffractive grating that is encoded with a permanent interference pattern or may be a switchable diffractive grating in which the diffracted light can be modulated by controlling an electric field applied to the holographic recording medium. Multiple holographic phase gratings (holograms) may be recorded within (e.g., superimposed within) the same volume of holographic medium if desired. The holographic phase gratings may be, for example, volume holograms or thin-film holograms in the grating medium. The grating media may include photopolymers, gelatin such as dichromated gelatin, silver halides, holographic polymer dispersed liquid crystal, or other suitable holographic media.

[0033] Diffractive gratings on waveguide 26 may include holographic phase gratings such as volume holograms or thin-film holograms, meta-gratings, or any other desired diffractive grating structures. The diffractive gratings on waveguide 26 may also include surface relief gratings formed on one or more surfaces of the substrates in waveguides 26, gratings formed from patterns of metal structures, etc. The diffractive gratings may, for example, include multiple multiplexed gratings (e.g., holograms) that at least partially overlap within the same volume of grating medium (e.g., for diffracting different colors of light and / or light from a range of different input angles at one or more corresponding output angles).

[0034] Optical system 14B may include collimating optics such as collimating optics 34 (sometimes referred to as collimating lens 34). Collimating lens 34 may include one or more lens elements and / or mirrors that help direct image light 22 towards waveguide 26. Ifdesired, display module 14A may be mounted within support structure 20 of FIG. 1 while optical system 14B may be mounted between portions of support structure 20 (e.g., to form a lens that aligns with eye box 24). Other mounting arrangements may be used, if desired.

[0035] As shown in FIG. 2, display 14 may include display modules 14A-1, 14A-2, and 14A-3 that are all associated with a single optical system 14B. As an example, the display modules may emit different colors of light (e.g., display module 14A-1 may emit red light, display module 14A-2 may emit blue light, and display module 14A-3 may emit green light).

[0036] When multiple display modules are included for a single optical system 14B, display 14 may include an optical combiner 36 (sometimes referred to as prism 36, X-cube 36, etc.). Optical combiner 36 may combine the light emitted by display modules 14A-1, 14A-2, and 14A-3 into image light 22 (e.g., image light 22 may include red, green, and blue light). The optical combiner may include angled surfaces that selectively reflect light based on color. The example of three display modules sharing an optical combiner in FIG. 2 is merely illustrative. The optical combiner and display modules 14A-1 and 14A-3 may optionally be omitted such that only one display module 14A is used to generate light 22 associated with image content to be displayed in eye box 24. Light 22 may be collimated using collimating optics 34. Optical system 14B may be used to present light 22 output from display module 14A to eye box 24.

[0037] Optical system 14B may include one or more optical couplers such as input coupler 28, cross-coupler 32, and output coupler 30. In the example of FIG. 2, input coupler 28, cross-coupler 32, and output coupler 30 are formed at or on waveguide 26. Input coupler 28, cross-coupler 32, and / or output coupler 30 may be completely embedded within the substrate layers of waveguide 26, may be partially embedded within the substrate layers of waveguide 26, may be mounted to waveguide 26 (e.g., mounted to an exterior surface of waveguide 26), etc.

[0038] The example of FIG. 2 is merely illustrative. One or more of these couplers (e.g., cross-coupler 32) may be omitted. Optical system 14B may include multiple waveguides that are laterally and / or vertically stacked with respect to each other. Each waveguide may include one, two, all, or none of couplers 28, 32, and 30. Waveguide 26 may be at least partially curved or bent if desired.

[0039] Waveguide 26 may guide light 22 down its length via total internal reflection. Input coupler 28 may be configured to couple light 22 from display module 14A (lens 34) intowaveguide 26, whereas output coupler 30 may be configured to couple light 22 from within waveguide 26 to the exterior of waveguide 26 and towards eye box 24. For example, display module 14A may emit light 22 in direction +Y towards optical system 14B. When light 22 strikes input coupler 28, input coupler 28 may redirect light 22 so that the light propagates within waveguide 26 via total internal reflection towards output coupler 30 (e.g., in the positive X-direction). When light 22 strikes output coupler 30, output coupler 30 may redirect light 22 out of waveguide 26 towards eye box 24 (e.g., in the negative Y-direction). In scenarios where cross-coupler 32 is formed at waveguide 26, cross-coupler 32 may redirect light 22 in one or more directions as it propagates down the length of waveguide 26, for example.

[0040] Input coupler 28, cross-coupler 32, and / or output coupler 30 may be based on reflective and refractive optics or may be based on holographic (e.g., diffractive) optics. In arrangements where couplers 28, 30, and 32 are formed from reflective and refractive optics, couplers 28, 30, and 32 may include one or more reflectors (e.g., an array of micromirrors, partial mirrors, or other reflectors). In arrangements where couplers 28, 30, and 32 are based on holographic optics, couplers 28, 30, and 32 may include diffractive gratings (e.g., volume holograms, surface relief gratings, etc.).

[0041] It may be desirable for collimating optics 34 to occupy a small volume in order to reduce the total size of electronic device 10. In some cases, collimating optics 34 may include a catadioptric lens element that both reflects and refracts the image light in order to provide a compact arrangement that collimates the image light. The catadioptric lens element may reflect the image light at least twice and may refract the image light at least twice. FIGS. 3-7 are top views of illustrative catadioptric collimating lenses 34.

[0042] As shown in FIG. 3, catadioptric collimating lens element 34 (sometimes referred to as lens element 34, lens 34, catadioptric lens element 34, catadioptric lens 34, catadioptric collimating lens 34, etc.) may include a plurality of discrete surfaces that reflect and refract image light 22 as the image light passes through the lens element. In the example of FIG. 3, lens element 34 includes 5 functional surfaces that reflect or refract light. The lens element of FIG. 3 may therefore sometimes be referred to as a 5-surface lens element.

[0043] As shown in FIG. 3, a first surface SI receives the light from optical combiner 36. Image light 22 is refracted when entering lens element 34 through surface SI. The image light is then incident upon surface S2 of lens element 34. A reflective layer 38-1 is formedon surface S2 and reflects the image light 22 towards surface S3. The image light is then incident upon surface S3 of lens element 34. The image light may reflect off of surface S3 due to the principle of total internal reflection (TIR). The image light is then incident upon surface S4 of lens element 34. A reflective layer 38-2 is formed on surface S4 and reflects the image light 22 towards surface S5. Image light 22 is refracted when exiting lens element 34 through surface S5. To summarize, lens element 34 of FIG. 3 refracts the image light twice (once at surface SI and once at surface S5) and reflects the image light three times (once at surface S2, once at surface S3, and once at surface S4).

[0044] After exiting lens element 34, image light 22 is incident upon waveguide 26 and may be coupled into the waveguide by input coupler 28.

[0045] Reflective layers 38-1 and 38-2 may have a reflectance that is greater than 80%, greater than 90%, greater than 95%, greater than 98%, etc. The reflective layers 38 may sometimes be referred to as mirrors 38. Mirrors 38 may have a reflectance that is greater than 70%, greater than 80%, greater than 90%, greater than 95%, greater than 98%, etc. The mirrors may be formed as coatings, films, or solid pieces. The mirrors may be attached or coated to a surface of lens element 34.

[0046] Lens element 34 may be formed from plastic, glass, or another desired transparent material. Lens element 34 may have a transparency that is greater than 70%, greater than 80%, greater than 90%, greater than 95%, greater than 98%, etc. The refractive index of lens element 34 may be greater than 1.3, greater than 1.4, greater than 1.5, greater than 1.6, greater than 1.7, greater than 1.8, etc.

[0047] Each one of surfaces SI, S2, S3, S4, and S5 in FIG. 3 may be a planar surface, a convex surface (e.g., a spherically convex surface, a cylindrically convex surface, or an aspherically convex surface), a concave surface (e.g., a spherically concave surface, a cylindrically concave surface, or an aspherically concave surface), or a freeform surface. A freeform surface may include two or more of planar portions, convex portions, and concave portions. A freeform surface may have varying convex curvatures or varying concave curvatures (e.g., different portions with different radii of curvature, portions with curvature in one direction and different portions with curvature in two directions, etc.). Herein, a freeform surface that is primarily convex (e.g., the majority of the surface is convex and / or the surface is convex at its center) may sometimes still be referred to as a convex surface and a freeform surface that is primarily concave (e.g., the majority of the surface is concave and / or thesurface is concave at its center) may sometimes still be referred to as a concave surface. In FIG. 3, surface SI is concave, surfaces S2 and S4 are convex, and surfaces S3 and S5 are planar.

[0048] Lens element 34 in FIG. 3 may have a dimension 40 parallel to the X-axis and a dimension 42 parallel to the Y-axis. Dimension 40 may be greater than 6 millimeters, greater than 9 millimeters, greater than 12 millimeters, less than 15 millimeters, etc. Dimension 42 may be greater than 2 millimeters, greater than 3 millimeters, greater than 5 millimeters, less than 6 millimeters, less than 5 millimeters, less than 4 millimeters, etc. As one specific example, dimension 40 may be less than 13 millimeters and dimension 42 may be less than 5 millimeters.

[0049] It is noted that lens element 34 may have additional non-functional surfaces not explicitly labeled in FIG. 3. These non-functional surfaces do not reflect or refract the image light and therefore the curvature of these surfaces does not impact the optical performance of lens 34. The shape of these non-functional surfaces may be selected to simplify manufacturing, as one example.

[0050] To simplify the manufacturing of lens element 34 and / or to reduce the size of lens element 34, the lens element may have 4 functional surfaces that reflect or refract light (instead of 5 functional surfaces as in FIG. 3).

[0051] In the example of FIG. 4, lens element 34 includes 4 functional surfaces that reflect or refract light. The lens element of FIG. 4 may therefore sometimes be referred to as a 4- surface lens element.

[0052] As shown in FIG. 4, a first surface SI receives the light from optical combiner 36. Image light 22 is refracted when entering lens element 34 through surface SI. The image light is then incident upon surface S2 of lens element 34. A reflective layer 38-1 is formed on surface S2 and reflects the image light 22 towards surface S3. The image light is then incident upon portion S3-1 of surface S3 of lens element 34. The image light may reflect off of surface S3 due to the principle of total internal reflection (TIR). The image light is then incident upon surface S4 of lens element 34. A reflective layer 38-2 is formed on surface S4 and reflects the image light 22 back towards surface S3. Image light 22 is refracted when exiting lens element 34 through portion S3-2 of surface S3. To summarize, lens element 34 of FIG. 4 refracts the image light twice (once at surface SI and once at portion S3 -2 of surface S3) and reflects the image light three times (once at surface S2, once at portion S3-1of surface S3, and once at surface S4). Surface S3 therefore both reflects the image light using total internal reflection (at portion S3-1) and refracts the image light exiting the lens element (at portion S3-2).

[0053] After exiting lens element 34, image light 22 is incident upon waveguide 26 and may be coupled into the waveguide by input coupler 28.

[0054] Each one of surfaces SI, S2, S3, and S4 in FIG. 4 may be a planar surface, a convex surface (e.g., a spherically convex surface, a cylindrically convex surface, or an aspherically convex surface), a concave surface (e.g., a spherically concave surface, a cylindrically concave surface, or an aspherically concave surface), or a freeform surface. In one specific example, surface SI is concave, surface S2 is convex, and surfaces S3 and S4 are planar.

[0055] Lens element 34 in FIG. 3 may have a dimension 40 parallel to the X-axis and a dimension 42 parallel to the Y-axis. Dimension 40 may be greater than 5 millimeters, greater than 6 millimeters, greater than 7 millimeters, less than 10 millimeters, less than 8 millimeters, etc. Dimension 42 may be greater than 2 millimeters, greater than 3 millimeters, greater than 5 millimeters, less than 6 millimeters, less than 5 millimeters, less than 4 millimeters, etc. As one specific example, dimension 40 may be less than 7 millimeters and dimension 42 may be less than 4 millimeters. Lens element 34 in FIG. 4 (with 4 functional surfaces) may have a smaller volume than lens element 34 in FIG. 3 (with 5 functional surfaces).

[0056] To enjoy the benefits of the smaller volume of the lens element of FIG. 4 while adding an additional functional surface for an additional degree of freedom, a low-index lens element may be attached to lens element 34 as shown in the example of FIG. 5.

[0057] As shown in FIG. 5, a first lens element 34-1 (with 4 functional surfaces similar to as shown in FIG. 4) is attached to a second lens element 34-2 using optically clear adhesive 44.

[0058] Lens element 34-1 may be formed from plastic, glass, or another desired transparent material. Lens element 34-1 may have a transparency that is greater than 70%, greater than 80%, greater than 90%, greater than 95%, greater than 98%, etc. The refractive index of lens element 34-1 may be greater than 1.3, greater than 1.4, greater than 1.5, greater than 1.6, greater than 1.7, greater than 1.8, etc.

[0059] Lens element 34-2 may be formed from plastic, glass, or another desired transparent material. Lens element 34-2 may have a transparency that is greater than 70%, greater than80%, greater than 90%, greater than 95%, greater than 98%, etc. The refractive index of lens element 34-2 may be less than 1.3, less than 1.4, less than 1.5, less than 1.6, less than 1.7, etc. Lens element 34-2 may have a lower refractive index than lens element 34-1. The difference between the refractive indices of lens elements 34-1 and 34-2 may be greater than 0.05, greater than 0.1, greater than 0.2, greater than 0.3, greater than 0.4, etc.

[0060] The optically clear adhesive (OCA) 44 may be index matched to lens element 34-2. The difference between the refractive indices of optically clear adhesive 44 and lens element 34-2 may be less than 0.1, less than 0.05, less than 0.03, less than 0.01, etc.

[0061] As shown in FIG. 5, a first surface SI receives the light from optical combiner 36. Image light 22 is refracted when entering lens element 34-1 through surface SI. The image light is then incident upon surface S2 of lens element 34-1. A reflective layer 38-1 is formed on surface S2 and reflects the image light 22 towards surface S3. The image light is then incident upon portion S3-1 of surface S3 of lens element 34-1. The image light may reflect off of surface S3 due to the principle of total internal reflection (TIR). The image light is then incident upon surface S4 of lens element 34-1. Image light 22 is refracted when exiting lens element 34-1 through surface S4 into lens element 34-2 (and intervening OCA 44). A reflective layer 38-2 is formed on surface S5 of lens element 34-2 and reflects the image light 22 back towards surface S4. Image light 22 is refracted when exiting lens element 34-2 (and OCA 44) through surface S4 back into lens element 34-1. Image light 22 is then refracted when exiting lens element 34-1 through portion S3-2 of surface S3. Surface S4 directly contacts OCA 44.

[0062] Lens elements 34-1 and 34-2 may collectively be referred to as a catadioptric collimating lens 34. Lens 34 of FIG. 5 refracts the image light four times (once at surface SI, twice at surface S4, and once at portion S3-2 of surface S3) and reflects the image light three times (once at surface S2, once at portion S3-1 of surface S3, and once at surface S5). Surface S3 therefore both reflects the image light using total internal reflection (at portion S3- 1) and refracts the image light exiting the lens element (at portion S3 -2).

[0063] After exiting lens element 34-1, image light 22 is incident upon waveguide 26 and may be coupled into the waveguide by input coupler 28.

[0064] Each one of surfaces SI, S2, S3, S4, and S5 in FIG. 5 may be a planar surface, a convex surface (e.g., a spherically convex surface, a cylindrically convex surface, or an aspherically convex surface), a concave surface (e.g., a spherically concave surface, acylindrically concave surface, or an aspherically concave surface), or a freeform surface. In one specific example, surface SI is concave, surface S2 is convex, and surfaces S3, S4, and S5 are planar.

[0065] Lens 34 in FIG. 5 may have a dimension 40 parallel to the X-axis and a dimension 42 parallel to the Y-axis. Dimension 40 may be greater than 5 millimeters, greater than 6 millimeters, greater than 7 millimeters, less than 10 millimeters, less than 8 millimeters, etc. Dimension 42 may be greater than 2 millimeters, greater than 3 millimeters, greater than 5 millimeters, less than 6 millimeters, less than 5 millimeters, less than 4 millimeters, etc. As one specific example, dimension 40 may be less than 7 millimeters and dimension 42 may be less than 4 millimeters. Lens element 34 in FIG. 5 (with 5 functional surfaces defined by two lens elements) may have a smaller volume than lens element 34 in FIG. 3 (with 5 functional surfaces defined by a single lens element).

[0066] The example in FIG. 5 of lens element 34-2 being attached to lens element 34-1 using OCA 44 is merely illustrative. If desired, lens element 34-1 may be overmolded over lens element 34-2 such that OCA 44 may be omitted.

[0067] To enjoy the benefits of the smaller volume of the lens element of FIG. 4 while adding two additional functional surfaces for two additional degrees of freedom, the 4- surface lens element may be split into two pieces with an intervening optically clear adhesive layer as shown in the example of FIG. 6.

[0068] As shown in FIG. 6, a first lens element 34-1 is attached to a second lens element 34-2 using optically clear adhesive 44. OCA 44 may optionally be omitted and an air gap may be included between lens elements 34-1 and 34-2 if desired.

[0069] Lens element 34-1 may be formed from plastic, glass, or another desired transparent material. Lens element 34-1 may have a transparency that is greater than 70%, greater than 80%, greater than 90%, greater than 95%, greater than 98%, etc. The refractive index of lens element 34-1 may be greater than 1.3, greater than 1.4, greater than 1.5, greater than 1.6, greater than 1.7, greater than 1.8, etc.

[0070] Lens element 34-2 may be formed from plastic, glass, or another desired transparent material. Lens element 34-2 may have a transparency that is greater than 70%, greater than 80%, greater than 90%, greater than 95%, greater than 98%, etc. The refractive index of lens element 34-2 may be greater than 1.3, greater than 1.4, greater than 1.5, greater than 1.6, greater than 1.7, greater than 1.8, etc.

[0071] Lens elements 34-1 and 34-2 may be formed from the same material (in which case the refractive indices of the lens elements may be the same) or from different materials. In the case of the lens elements being formed from different materials, the difference in refractive index between lens elements 34-1 and 34-2 may be less than 0.3, less than 0.2, less than 0.1, less than 0.05, less than 0.03, less than 0.01, etc.

[0072] Optically clear adhesive 44 may have a different refractive index than lens elements 34-1 and 34-2 such that the image light is refracted when entering and exiting the optically clear adhesive. The difference in refractive index between OCA 44 and lens element 34-1 may be greater than 0.05, greater than 0.1, greater than 0.2, greater than 0.3, greater than 0.4, etc. The difference in refractive index between OCA 44 and lens element 34-2 may be greater than 0.05, greater than 0.1, greater than 0.2, greater than 0.3, greater than 0.4, etc.

[0073] As shown in FIG. 6, a first surface SI receives the light from optical combiner 36. Image light 22 is refracted when entering lens element 34-1 through surface SI. The image light is then incident upon surface S2 of lens element 34-1. A reflective layer 38-1 is formed on surface S2 and reflects the image light 22 towards surface S3. The image light is refracted when passing through surface S3 from lens element 34-1 into OCA 44. The image light is then refracted again when passing through surface S4 from OCA 44 into lens element 34-2. The image light is then incident upon portion S5-1 of surface S5 of lens element 34-2. The image light may reflect off of surface S5 due to the principle of total internal reflection (TIR). The image light is then incident upon surface S6 of lens element 34-2. A reflective layer 38- 2 is formed on surface S6 of lens element 34-2 and reflects the image light 22 back towards surface S5. Image light 22 is then refracted when exiting lens element 34-2 through portion S5-2 of surface S5. Surfaces S3 and S4 directly contact OCA 44.

[0074] Lens elements 34-1 and 34-2 may collectively be referred to as a catadioptric collimating lens 34. Lens 34 of FIG. 6 refracts the image light four times (once at surface SI, once at surface S3, once at surface S4, and once at portion S5-2 of surface S5) and reflects the image light three times (once at surface S2, once at portion S5-1 of surface S5, and once at surface S6). Surface S5 therefore both reflects the image light using total internal reflection (at portion S5-1) and refracts the image light exiting the lens element (at portion S5-2).

[0075] After exiting lens element 34-2, image light 22 is incident upon waveguide 26 and may be coupled into the waveguide by input coupler 28.

[0076] Each one of surfaces SI, S2, S3, S4, S5, and S6 in FIG. 6 may be a planar surface, a convex surface (e.g., a spherically convex surface, a cylindrically convex surface, or an aspherically convex surface), a concave surface (e.g., a spherically concave surface, a cylindrically concave surface, or an aspherically concave surface), or a freeform surface. In one specific example, surface SI is concave, surfaces S2 and S4 are convex, and surfaces S3, S5 and S6 are planar.

[0077] Lens 34 in FIG. 6 may have a dimension 40 parallel to the X-axis and a dimension 42 parallel to the Y-axis. Dimension 40 may be greater than 5 millimeters, greater than 6 millimeters, greater than 7 millimeters, less than 10 millimeters, less than 8 millimeters, etc. Dimension 42 may be greater than 2 millimeters, greater than 3 millimeters, greater than 5 millimeters, less than 6 millimeters, less than 5 millimeters, less than 4 millimeters, etc. As one specific example, dimension 40 may be less than 7 millimeters and dimension 42 may be less than 4 millimeters. Lens element 34 in FIG. 6 (with 6 functional surfaces defined by two lens elements) may have a smaller volume than lens element 34 in FIG. 3 (with 5 functional surfaces defined by a single lens element).

[0078] To simplify the manufacturing of lens 34 and / or to reduce the size of lens 34, the lens may have 3 functional surfaces that reflect or refract light (instead of 4 as in FIG. 4). In the example of FIG. 7, lens element 34 includes 3 functional surfaces that reflect or refract light. The lens element of FIG. 7 may therefore sometimes be referred to as a 3-surface lens element.

[0079] As shown in FIG. 7, a first portion Sl-1 of a first surface SI receives the light from optical combiner 36 (and intervening waveguide 26). Image light 22 is refracted when entering lens element 34 through surface SI. The image light is then incident upon surface S2 of lens element 34. A reflective layer 38-1 is formed on surface S2 and reflects the image light 22 back towards surface SI. The image light is then incident upon portion SI -2 of surface SI of lens element 34. The image light may reflect off of surface SI due to the principle of total internal reflection (TIR). The image light is then incident upon surface S3 of lens element 34. A reflective layer 38-2 is formed on surface S3 and reflects the image light 22 back towards surface S 1. Image light 22 is refracted when exiting lens element 34 through portion SI -3 of surface SI. To summarize, lens element 34 of FIG. 4 refracts the image light twice (once at portion Sl-1 of surface SI and once at portion SI -3 of surface SI) and reflects the image light three times (once at surface S2, once at portion SI -2 of surfaceSI, and once at surface S3). Surface SI therefore refracts the image light entering the lens element (at portion Sl-1), reflects the image light using total internal reflection (at portion SI -2), and refracts the image light exiting the lens element (at portion SI -3).

[0080] After exiting lens element 34, image light 22 is incident upon waveguide 26 and may be coupled into the waveguide by input coupler 28.

[0081] Each one of surfaces SI, S2, and S3 in FIG. 7 may be a planar surface, a convex surface (e.g., a spherically convex surface, a cylindrically convex surface, or an aspherically convex surface), a concave surface (e.g., a spherically concave surface, a cylindrically concave surface, or an aspherically concave surface), or a freeform surface. In one specific example, surfaces SI, S2, and S3 are all planar.

[0082] Lens element 34 in FIG. 7 may have a dimension 40 parallel to the X-axis and a dimension 42 parallel to the Y-axis. Dimension 40 may be greater than 5 millimeters, greater than 6 millimeters, greater than 7 millimeters, less than 10 millimeters, less than 8 millimeters, etc. Dimension 42 may be greater than 2 millimeters, greater than 3 millimeters, greater than 5 millimeters, less than 6 millimeters, less than 5 millimeters, less than 4 millimeters, etc. Lens element 34 in FIG. 7 (with 3 functional surfaces) may have a smaller volume than lens element 34 in FIG. 3 (with 5 functional surfaces).

[0083] In the example of FIG. 7, image light exits optical combiner 36 and passes through waveguide 26 before being incident upon lens 34. The portion of waveguide 26 that receives the light from optical combiner 36 may refract the image light and therefore may be considered part of the collimating optics for the optical system. The example of waveguide 26 being interposed in the optical path of image light between optical combiner 36 and lens element 34 in FIG. 7 is merely illustrative. If desired, the waveguide may not be interposed between optical combiner 36 and lens element 34 in FIG. 7 if desired. Similarly, the waveguide may optionally be interposed in the optical path of image light between optical combiner 36 and lens 34 in FIGS. 3-6 if desired.

[0084] FIG. 5 shows how a low-index lens element may be attached to a lens element to provide an additional refractive surface within lens 34. This provides an additional degree of freedom within the system. In general, any of the lens elements shown herein in FIGS. 3-9 may be attached to an additional low-index lens element to create an additional refractive surface within the lens.

[0085] FIG. 6 shows how a given lens element may be split into two lens elements toprovide two additional refractive surfaces within lens 34. This provides two additional degrees of freedom within the system. In general, any of the lens elements shown herein in FIGS. 3-7 may be split into multiple lens elements with intervening OCA to create additional refractive surfaces within the lens. It is noted that the OCA may optionally be omitted and an air gap may be included between adjacent lens elements if desired.

[0086] In FIGS. 3-7, light is reflected using TIR one time within lens 34 (e.g., at surface S3 in FIG. 3, at portion S3-1 of surface S3 in FIGS. 4 and 5, at portion S5-1 of surface S5 in FIG. 6, and at portion SI -2 of surface SI in FIG. 7). It is noted that an additional reflective layer 38 may instead be included at these surfaces instead of relying on TIR. This may allow additional flexibility within the system (as the lens will not be constrained to using TIR at this surface).

[0087] The example in FIGS. 3-7 of the display modules and optical combiner being formed on the negative Y-side of waveguide 26 (e.g., on the same side of the waveguide as the eye box) and catadioptric lens 34 being formed on the positive Y-side of the waveguide 26 (e.g., on the opposite side of the waveguide as the eye box) is merely illustrative. If desired, this arrangement may be flipped and the display modules and optical combiner may be formed on the positive Y-side of waveguide 26 (e.g., on the opposite side of the waveguide as the eye box) and catadioptric lens 34 may be formed on the negative Y-side of the waveguide 26 (e.g., on the same side of the waveguide as the eye box). Along the X- direction, the display modules, optical combiner, and catadioptric lens may be formed on the nasal side of the display system (e.g., in a region configured to overlap the user’s nose when device 10 is worn by the user) or on the temple side of the display system (e.g., in a region configured to overlap the user’s temple when device 10 is worn by the user).

[0088] In one possible arrangement, the display modules, optical combiners, and catadioptric lenses associated with both the left and right eyes of the user may be formed on the nasal side of the display system (e.g., in a region configured to overlap the user’s nose when device 10 is worn by the user). In this arrangement, a first catadioptric lens may be used to collimate light for a first waveguide associated with the user’s left eye and second catadioptric lens may be used to collimate light for a second waveguide associated with the user’s right eye. The first and second catadioptric lenses may both overlap the nasal region of device 10.

[0089] FIG. 8 is a top view of an illustrative display system for a left and right eye of theuser. As shown in FIG. 8, display system 14 includes a first waveguide 26-L that is configured to direct light to a left eye of the user and a second waveguide 26-R that is configured to direct light to a right eye of the user. Each one of waveguides 26-L and 26-R may include an input coupler 28, cross-coupler 32, and / or output coupler 30 as shown and described in connection with FIG. 2. FIG. 8 shows input coupler 28-L for waveguide 26-L and input coupler 28-R for waveguide 26-R.

[0090] As shown in FIG. 8, a first catadioptric collimating lens element 34-L (sometimes referred to as lens element 34-L, lens 34-L, catadioptric lens element 34-L, catadioptric lens 34-L, catadioptric collimating lens 34-L, etc.) may collimate light for waveguide 26-L. A second catadioptric collimating lens element 34-R (sometimes referred to as lens element 34- R, lens 34-R, catadioptric lens element 34-R, catadioptric lens 34-R, catadioptric collimating lens 34-R, etc.) may collimate light for waveguide 26-R. Lens elements 34-L and 34-R in FIG. 8 may each have the same structure as lens element 34 in FIG. 3.

[0091] Lens element 34-R has a first surface Sl-R with concave curvature, a second surface52-R with convex curvature, a third surface S3-R that is planar, a fourth surface S4-R with convex curvature, and a fifth surface S5-R that is planar. Light from one or more display modules may be refracted by surface Sl-R, reflected by surface S2-R, reflected by surface53-R (e.g., by total internal reflection), reflected by surface S4-R, and refracted by surface S5-R to direct light to input coupler 28-R.

[0092] A reflective layer 38-1 is formed on surface S2-R and reflects the image light towards surface S3-R. A reflective layer 38-2 is formed on surface S4-R and reflects the image light towards surface S5-R.

[0093] Lens element 34-L may have the same structure as lens element 34-R. Lens element 34-L has a first surface Sl-L with concave curvature, a second surface S2-L with convex curvature, a third surface S3-L that is planar, a fourth surface S4-L with convex curvature, and a fifth surface S5-L that is planar. Light from one or more display modules may be refracted by surface Sl-L, reflected by surface S2-L, reflected by surface S3-L (e.g., by total internal reflection), reflected by surface S4-L, and refracted by surface S5-L to direct light to input coupler 28-L.

[0094] A reflective layer 38-4 is formed on surface S2-L and reflects the image light towards surface S3-L. A reflective layer 38-3 is formed on surface S4-L and reflects the image light towards surface S5-R.

[0095] In FIG. 8, display system 14 includes a first optical combiner 36-L that merges light from display modules 14A-1, 14A-2, and 14A-3. Optical combiner 36-L outputs the light to collimating lens 34-L for waveguide 26-L. Display system 14 also includes a second optical combiner 36-R that merges light from display modules 14A-4, 14A-5, and 14A-6. Optical combiner 36-R outputs the light to collimating lens 34-R for waveguide 26-R.

[0096] In the arrangement of FIG. 8, display system 14 therefore includes two discrete optical combiners 36 in the nasal region of the display system for two respective collimating lenses 34. In the arrangement of FIG. 8, there are six display modules in the nasal region of the device, with three respective display modules providing light to each optical combiner.

[0097] In another possible arrangement, shown in FIG. 9, a single optical combiner 36 may be shared between collimating lenses 34-L and 34-R. As shown in FIG. 9, a single optical combiner may receive image light from display modules 14A-1, 14A-2, 14A-3, 14A-4, 14A- 5, and 14A-6. The shared optical combiner may provide the light from display modules 14A- 1, 14A-2, and 14A-3 to lens element 34-L while simultaneously providing the light from display modules 14A-4, 14A-5, and 14A-6 to lens element 34-R.

[0098] In yet another possible arrangement, shown in FIG. 10, a single optical combiner 36 and three display modules may be shared between collimating lenses 34-L and 34-R. As shown in FIG. 10, a single optical combiner may receive image light from display modules 14A-1, 14A-2, and 14A-3. The shared optical combiner may provide a first portion of the light from display modules 14A-1, 14A-2, and 14A-3 to lens element 34-L while simultaneously providing a second portion of the light from display modules 14A-1, 14A-2, and 14A-3 to lens element 34-R.

[0099] The display modules of FIGS. 8-10 each may include a respective backplane and a respective active area. The backplane comprises a substrate and driving circuitry (e.g., thin- film transistors) that control pixels in the display module. The active area comprises an array of light sources (pixels) that emit light (as controlled by the backplane). In FIGS. 8 and 9, there are six display modules that each have a respective backplane and active area. In FIG. 10, there are three display modules that each have a respective backplane and active area. These examples are merely illustrative and if desired multiple active areas may share a common backplane. For example, in a given display system, two discrete active areas with red light sources (one active area that primarily emits light into lens 34-L and one active area that primarily emits light into lens 34-R) may share a first common backplane, two discreteactive areas with green light sources (one active area that primarily emits light into lens 34-L and one active area that primarily emits light into lens 34-R) may share a second common backplane, and two discrete active areas with blue light sources (one active area that primarily emits light into lens 34-L and one active area that primarily emits light into lens 34- R) may share a third common backplane.

[0100] The example in FIGS. 8-10 where each lens element 34 has the same arrangement as FIG. 3 is merely illustrative. In general, each lens element 34 in FIGS. 8-13 may have the same arrangement as any of the lens elements of FIGS. 3-7 or any other desired arrangement.

[0101] When a single optical combiner 36 is used to provide image light to both collimating lenses 34-L and 34-R, crosstalk mitigating features may optionally be included in display system 14. FIGS. 11 A-l 1C are side views of an illustrative optical combiner that is used to provide image light to both collimating lenses 34-L and 34-R and that has crosstalk mitigating features.

[0102] As shown in FIGS. 11 A-l 1C, optical combiner 36 may direct light from three display modules such as display modules 14A-1, 14A-2, and 14A-3 to collimating lens 34-L. Only display module 14A-2 is explicitly pictured in FIGS. 11 A-l 1C. Display modules 14A-I and 14A-3 may be formed above and below the optical combiner and are therefore not explicitly shown in FIGS. 11 A-l 1C so as to not obfuscate the drawings. Optical combiner 36 may also direct light from three display modules such as display modules 14A-4, 14A-5, and 14A-6 to collimating lens 34-R. Only display module 14A-5 is explicitly pictured in FIGS.I I A-l 1C. Display modules 14A-4 and 14A-6 may be formed above and below the optical combiner and are therefore not explicitly shown in FIGS. 11 A-l 1C so as to not obfuscate the drawing.

[0103] In the example of FIG. 11 A, optical combiner 36 includes one or more roughened portions 52 (sometimes referred to as roughened surfaces 52, rough surfaces 52, etc.). Optical combiner 36 may have outer surfaces formed from a material such as glass. Portions 52 of the outer surface of the optical combiner may be rougher than the surrounding portions of the outer surface of the optical combiner. The rough portions 52 may promote scattered reflection, mitigating specular reflections that may cause crosstalk (e.g., ghost images).

[0104] In the example of FIG. 11 A, a first rough portion 52-1 is formed on a first surface of optical combiner 36 that is adjacent to lenses 34. The first surface serves as an exit surface for the optical combiner and light exits the first surface towards lenses 34-L and 34-R. Thefirst rough portion 52-1 is interposed between lens 34-L and 34-R on the first surface. A second rough portion 52-2 is formed on a second, opposing surface of optical combiner 36 that is adjacent to display modules 14A-2 and 14A-5. The second surface serves as an entrance surface for the optical combiner and light enters the second surface from display modules 14A-2 and 14A-5. The second rough portion 52-2 is interposed between display modules 14A-2 and 14A-5 on the second surface.

[0105] Instead or in addition to having a rougher texture than surrounding portions of the optical combiner, portions 52 of the optical combiner may be coated with ink. As shown in FIG. 11 A, a first ink coating 54-1 may be formed on rough portion 52-1 of the optical combiner and a second ink coating 54-2 may be formed on rough portion 52-2 of the optical combiner. The ink coatings 54 may be formed from black ink or another material that absorbs incident light. The ink may therefore absorb incident light and mitigate reflections within the optical combiner that may otherwise cause crosstalk.

[0106] In another possible arrangement, shown in FIG. 1 IB, optical combiner 36 may include one or more baffles. The baffles may comprise light blocking structures that mitigate crosstalk between lens elements 34-L and 34-R. As shown in FIG. 1 IB, a first baffle may extend from a first side of the optical combiner towards a second side of the optical combiner (e.g., in the negative Y-direction). A second baffle may extend from the second side of the optical combiner towards the first side of the optical combiner (e.g., in the positive Y- direction). Each baffle may be planar (e.g., parallel to the YZ-plane and extending into and out of the page in FIG. 1 IB). Each baffle may be interposed between left lens element 34-L and right lens element 34-R (e.g., along the X-direction). Each baffle may be interposed between display modules 14A-2 and 14A-5 (e.g., along the X-direction).

[0107] The baffles may be offset in the X-direction. Offsetting the baffles allows for the baffles to overlap at portion 58. The overlap portion 58 may help prevent light from passing through the baffles from a first side of the optical combiner to a second side of the optical combiner (thus mitigating crosstalk). Optical combiner 34 may have a first dimension parallel to the Y-axis. Baffle 56-1 may have a second dimension parallel to the Y-axis. Baffle 56-2 may have a third dimension parallel to the Y-axis. Each one of the second and third dimensions may be less than the first dimension. The sum of the second and third dimensions may be greater than the first dimension.

[0108] The example in FIG. 1 IB of having two baffle structures is merely illustrative. Ifdesired, either baffle 56-1 or baffle 56-2 may be omitted.

[0109] Each one of baffles 56-1 and 56-2 may be formed by cutting out a portion of optical combiner 36. For example, when optical combiner 36 is formed from glass the glass may be cut to form openings for each one of baffles 56-1 and 56-2. Light absorbing ink may subsequently be used to fill the openings and define the baffles.

[0110] In another possible arrangement, shown in FIG. 11C, one or more functional layers may be attached to optical combiner 36 to mitigate crosstalk. As shown in FIG. 11C, first functional layers 60 may be attached to an exit surface of optical combiner 36 where light passes through the optical combiner towards lens elements 34-L and 34-R. Second function layers 62 may be attached to an entrance surface of optical combiner 36 where light passes from display modules 14A into the optical combiner. The functional layers 62 may optionally be attached to display modules 14A instead of to the optical combiner itself. Similarly, the functional layers 60 may optionally be attached to lens elements 34 instead of to the optical combiner itself.

[0111] The functional layers may include one or more layers that manipulate the polarization of light passing through the optical combiner. In general functional layers 60 may include a linear polarizer, a retarder such as a quarter wave plate, etc. Functional layers 62 may also include a linear polarizer, a retarder such as a quarter wave plate, etc. As one example, the functional layer 62-L overlapping display module 14A-2 may include a linear polarizer with a pass axis that is parallel to the X-axis. The functional layer 60-L overlapping lens element 34-L may include a linear polarizer with a pass axis that is parallel to the X-axis. The functional layer 62-R overlapping display module 14A-5 may include a linear polarizer with a pass axis that is parallel to the Z-axis. The functional layer 60-R overlapping lens element 34-R may include a linear polarizer with a pass axis that is parallel to the Z-axis. With this arrangement, light from display module 14A-2 that enters optical combiner 36 through linear polarizer 62-L will not be able to pass through linear polarizer 60-R.Similarly, light from display module 14A-5 that enters optical combiner 36 through linear polarizer 62-R will not be able to pass through linear polarizer 60-L.

[0112] As other examples, functional layers 60 and 62 may include louver films that narrow the range of angles that pass through the films, high-angle rejection coatings that block light at high incidence angles, etc. The functional layers may therefore optionally block some or all light that is incident upon the layer at an angle that deviates from the surface normal of the 1layer by more than 10 degrees, more than 20 degrees, more than 30 degrees, more than 45 degrees, more than 60 degrees, etc.

[0113] To integrate display system 14 into head-mounted device 10, one or more components of display module(s) 14A and / or optical system(s) 14B may be incorporated into a projector module. FIGS. 12A-12D are views of an illustrative projector module 102 (sometimes referred to as display module 102, optical module 102, etc.). FIG. 12A shows a cross-sectional view along a cross-sectional plane that extends through a middle of the projector module (and therefore extends through the gap between lenses 34-L and 34-R and is not aligned with any display modules). FIG. 12B shows a cross-sectional view from the same perspective as FIG. 12A but aligned with the display modules. FIGS. 12C and 12D show views of the projector module from two additional sides compared to FIGS. 12A and 12B.

[0114] As shown in FIGS. 12A-12D, the projector module may include a number of components integrated into a unitary package. Optical combiner 36 (which is shared by lenses 34-R and 34-L) is held (housed) within and attached to a first chassis 108. Lenses 34- R and 34-L are also held (housed) within and attached to first chassis 108. Chassis 108 has a first portion 108-OC that is attached to optical combiner 36 (as shown in FIG. 12D) and a second portion 108-L that is attached to lens elements 34-L and 34-R (as shown in FIGS. 12A and 12B).

[0115] Portion 108-OC of chassis 108 may include a plurality of openings that accommodate display modules that emit light into optical combiner 36. Projector module 102 may include a first display module 14A-1 that emits red light for lens 34-L and waveguide 26-L, a second display module 14A-2 that emits green light for lens 34-L and waveguide 26-L, a third display module 14A-3 that emits blue light for lens 34-L and waveguide 26-L, a fourth display module 14A-4 that emits red light for lens 34-R and waveguide 26-R, a fifth display module 14A-5 that emits green light for lens 34-R and waveguide 26-R, and a sixth display module 14A-6 that emits blue light for lens 34-R and waveguide 26-R. Each one of display modules 14A-1, 14A-2, 14A-3, 14A-4, 14A-5, and 14A-6 may align with and / or protrude through a corresponding opening in portion 108-OC of chassis 108. Each one of display modules 14A-1, 14A-2, 14A-3, 14A-4, 14A-5, and 14A-6 may emit light into optical combiner 36.

[0116] A flexible printed circuit 104 may be bonded to display modules 14A-1, 14A-2,14A-3, 14A-4, 14A-5, and 14A-6. Flexible printed circuit 104 may include a plurality of portions each bonded to a corresponding display module. Flexible printed circuit 104 also includes a plurality of bends to accommodate the positions of the display modules. Tape may optionally overlap flexible printed circuit 104. The tape may provide electromagnetic interference (EMI) shielding and / or thermal conductivity to dissipate heat within module 102. The tape may include copper, aluminum, polymer, or any other desired material.

[0117] Display modules 14A-1, 14A-2, 14A-3, 14A-4, 14A-5, and 14A-6 surround portion 108-OC of chassis 108 on three sides. Flexible printed circuit 104 conforms to display modules 14A-1, 14A-2, 14A-3, 14A-4, 14A-5, and 14A-6 and surrounds portion 108-OC of chassis 108 on three sides. When included, the optional tape may conform to flexible printed circuit 104 and surround portion 108-OC of chassis 108 on three sides.

[0118] As shown in FIGS. 12A and 12B, portion 108-L may include a first portion 108-L1 and a second portion 108-L2. Portion 108-L 1 may extend away from a top side of portion 108-OC in FIG. 12. Portion 108-L2 may extend away from a bottom side of portion 108-OC. Portions 108-L 1 and 108-L2 may optionally be non-parallel and may extend away from each other at a non-zero angle. Portion 108-L1 may be attached to a top surface of both lenses 34- L and 34-R. Portion 108-L2 may be attached to a bottom surface of both lenses 34-L and 34- R.

[0119] A second chassis 110 may be attached to chassis 108. In particular, chassis 110 is attached to portion 108-L of chassis 108. Chassis 110 has an opening 110-0 that accommodates a mounting post that is used to attach and align projector module 102 within device 10. Adhesive 112 may be formed within opening 110-0 to attach chassis 110 to housing 20 of device 10.

[0120] Lenses 34-L and 34-R may optionally protrude between a gap between chassis 108 and chassis 110. Lenses 34-L and 34-R may be at least partially interposed between chassis 108 and chassis 110.

[0121] FIGS. 12A and 12B show how different portions of optical combiner 36 receive different colors of light. A first portion R of optical combiner 36 receives red light from display modules 14A-1 and 14A-4. A second portion B of optical combiner 36 receives blue light from display modules 14A-3 and 14A-6. A third portion G of optical combiner 36 receives green light from display modules 14A-2 and 14A-5. A fourth portion W of optical combiner 36 outputs white light towards lenses 34-L and 34-R.

[0122] FIGS. 12A and 12B show an adhesive layer 114-1 that may be used to attach an upper surface of chassis 110 to a lower surface of portion 108-L1 of chassis 108. There is additionally an adhesive layer 114-2 that may be used to attach a lower surface of chassis 110 to an upper surface of portion 108-L2 of chassis 108.

[0123] As shown in FIG. 12A, adhesive layer 112 conforms to opening 110-0 in chassis 110. The opening 110-0 may extend only partially through chassis 110.

[0124] As shown in FIG. 12B, an adhesive layer 114-3 may be used to attach an upper surface of lens 34-L to a lower surface of portion 108-L1 of chassis 108. There is additionally an adhesive layer 114-4 that may be used to attach a lower surface of lens 34-L to an upper surface of portion 108-L2 of chassis 108. One or more adhesive layers 114 may attach display module 14A-1 to portion 108-OC of chassis 108. Display module 14A-1 is aligned with (and may protrude through) an opening in portion 108-OC that is interposed between two adhesive layer portions 114. One or more adhesive layers 114 may attach display module 14A-2 to portion 108-OC of chassis 108. Display module 14A-2 is aligned with (and may protrude through) an opening in portion 108-OC that is interposed between two adhesive layer portions 114. One or more adhesive layers 114 may attach display module 14A-3 to portion 108-OC of chassis 108. Display module 14A-3 is aligned with (and may protrude through) an opening in portion 108-OC that is interposed between two adhesive layer portions 114.

[0125] Each one of the adhesive layer portions in FIG. 12B is attached to the left half of projector module 102. For each one of these adhesive layers (or adhesive layers portions), there may be a duplicate adhesive layer (or a portion of the same adhesive layer) in a symmetric arrangement for the right half of the projector module. Lens element 34-R may have an upper surface attached to portion 108-L1 and a lower surface attached to portion 108- L2 by respective adhesive layers. One or more adhesive layers 114 may attach display module 14A-4 to portion 108-OC of chassis 108. Display module 14A-4 is aligned with (and may protrude through) an opening in portion 108-OC that is interposed between two adhesive layer portions 114. One or more adhesive layers 114 may attach display module 14A-5 to portion 108-OC of chassis 108. Display module 14A-5 is aligned with (and may protrude through) an opening in portion 108-OC that is interposed between two adhesive layer portions 114. One or more adhesive layers 114 may attach display module 14A-6 to portion 108-OC of chassis 108. Display module 14A-6 is aligned with (and may protrude through)an opening in portion 108-OC that is interposed between two adhesive layer portions 114.

[0126] FIG. 12B shows how a given display module such as display module 14A-1 may include a first active area AA-1 and a first backplane BP-1. In the arrangement shown in FIGS. 12A-12D, each display module has a discrete respective active area and a discrete respective backplane. However, the backplanes of display modules 14A-1 and 14A-4 may be merged into a common backplane if desired (as indicated by the dashed lines in FIG. 12C). Similarly, the backplanes of display modules 14A-2 and 14A-5 may be merged into a common backplane if desired and the backplanes of display modules 14A-3 and 14A-6 may be merged into a common backplane if desired (as indicated by the dashed lines in FIG. 12C).

[0127] FIG. 12D shows that there may be an air gap 116 between lenses 34 and chassis 110. FIG. 12C shows that there may be a gap 118 between adjacent display modules of the same color such as between display modules 14A-1 and 14A-4, between display modules 14A-2 and 14A-5, and between display modules 14A-3 and 14A-6.

[0128] Optical combiner 36 may optionally be attached to portion 108-OC of chassis 108 by one or more adhesive layers. FIG. 12D further shows that chassis 110 may have a first surface 110-S1 with curvature that conforms to the curvature of an adjacent surface in lens 34-L and a second surface 110-S2 with curvature that conforms to the curvature of an adjacent surface in lens 34-R.

[0129] The adhesive layer(s) 114 that attach display modules 14A to chassis 108 may comprise rings of adhesive that surround each respective opening in chassis portion 108-OC, multiple discrete layers of adhesive that at least partially surround each respective opening in chassis portion 108-OC, etc.

[0130] FIG. 13 is a cross-sectional view of a projector module 102 in a housing 20 of device 10. As shown, projector module 102 has the same arrangement as in FIGS. 12A-12D. Lens 34-R has a first portion that overlaps optical combiner 36 in the Y-direction and a second portion that overlaps waveguide 26-R in the Y-direction. The first portion of lens 34- R may receive image light from the optical combiner. The image light may exit the second portion of lens 34-R towards waveguide 26-R. Lens 34-L has a first portion that overlaps optical combiner 36 in the Y-direction and a second portion that overlaps waveguide 26-L in the Y-direction. The first portion of lens 34-L may receive image light from the optical combiner. The image light may exit the second portion of lens 34-L towards waveguide 26- L.

[0131] FIG. 13 further shows how projector module 102 may be housed by housing 20 of device 10. Projector module 102 is interposed between first and second housing structures 20-1 and 20-2. Housing structures 20-1 and 20-2 may be formed from metal, plastic, glass, etc. Housing structure 20-2 may have an integral mounting post 20-MP that extends in the negative Y-direction. The example of mounting post 20-MP being formed integrally with housing structure 20-2 is merely illustrative and the mounting post may optionally be attached to housing structure 20-MP (e.g., using adhesive). The mounting post 20-MP may protrude into opening 110-0 of chassis 110 and be attached to chassis 110 by adhesive layer 112. Mounting post 20-MP therefore mates with opening 110-0. Mounting post 20-MP may be the only attachment point between projector module 102 and housing 20. Alternatively, one or more additional attachment points may be included between projector module 102 and housing 20 if desired.

[0132] FIG. 14A is a top view of an illustrative display module 14A. The display module may include an array of light sources 202. The light sources may be light-emitting diodes or other desired types of light sources. Each light-emitting diode has a respective center 202-C. The light-emitting diodes may be arranged in rows and columns. Adjacent columns of lightemitting diodes may be separated by a horizontal pitch 204-H (e.g., a center-to-center pitch). Adjacent rows of light-emitting diodes may be separated by a vertical pitch 204-V (e.g., a center-to-center pitch).

[0133] FIG. 14B is a top view of the illustrative display module from FIG. 14A. FIG. 14B shows how an array of microlenses may overlap the array of light-emitting diodes 202. The array of light-emitting diodes 202 therefore emits light through the array of microlenses 206. The microlenses may be arranged in rows and columns. Each microlens has a respective center 206-C. Adjacent columns of microlenses may be separated by a horizontal pitch 208- H (e.g., a center-to-center pitch). Adjacent rows of microlenses may be separated by a vertical pitch 208-V (e.g., a center-to-center pitch).

[0134] To improve efficiency and manufacturing tolerance in display module 14A, pitch 204-H may be different than pitch 208-H and pitch 204-V may be different than pitch 208-V. Pitch 208-H may be greater than pitch 204-H by at least 1%, at least 3%, at least 5%, at least 10%, at least 20%, at least 30%, between 1% and 30%, etc., less than 50%, less than 25%, etc. Pitch 208-H may be less than pitch 204-H by at least 1%, at least 3%, at least 5%, at least 10%, at least 20%, at least 30%, between 1% and 30%, etc., less than 50%, less than25%, etc. Pitch 208-V may be greater than pitch 204-V by at least 1%, at least 3%, at least 5%, at least 10%, at least 20%, at least 30%, between 1% and 30%, etc., less than 50%, less than 25%, etc. Pitch 208-V may be less than pitch 204-V by at least 1%, at least 3%, at least 5%, at least 10%, at least 20%, at least 30%, between 1% and 30%, etc., less than 50%, less than 25%, etc.

[0135] In accordance with an embodiment, a display system includes a first waveguide, a second waveguide, an optical combiner that is interposed between the first and second waveguides, a first catadioptric lens that is interposed between the first and second waveguides and that redirects first image light from the optical combiner to the first waveguide, a second catadioptric lens that is interposed between the first and second waveguides and that redirects second image light from the optical combiner to the second waveguide, and a plurality of display modules that provides the first image light and the second image light to the optical combiner.

[0136] In accordance with another embodiment, the plurality of display modules optionally includes three display modules that provide both the first image light and the second image light to the optical combiner.

[0137] In accordance with another embodiment, the plurality of display modules optionally includes first, second, and third display modules that provide the first image light to the optical combiner and fourth, fifth, and sixth display modules that provide the second image light to the optical combiner.

[0138] In accordance with another embodiment, the plurality of display modules optionally includes first and second active areas that share a first common backplane, third and fourth active areas that share a second common backplane, and fifth and sixth active areas that share a third common backplane.

[0139] In accordance with another embodiment, the optical combiner optionally includes a surface with a first portion that is rougher than a second portion.

[0140] In accordance with another embodiment, the surface is optionally an exit surface of the optical combiner through which the first image light exits towards the first catadioptric lens and the second image light exits towards the second catadioptric lens.

[0141] In accordance with another embodiment, the surface is optionally an entrance surface of the optical combiner through which the first image light and the second image light enter the optical combiner from the plurality of display modules.

[0142] In accordance with another embodiment, the display system optionally includes an ink coating on a surface of the optical combiner.

[0143] In accordance with another embodiment, the optical combiner optionally includes at least one baffle.

[0144] In accordance with another embodiment, the display system optionally includes a louver film that is interposed between the optical combiner and at least one of the plurality of display modules or interposed between the optical combiner and at least one of the first and second catadioptric lenses.

[0145] In accordance with another embodiment, the display system optionally includes a linear polarizer that is interposed between the optical combiner and at least one of the plurality of display modules or interposed between the optical combiner and at least one of the first and second catadioptric lenses.

[0146] In accordance with another embodiment, the display system optionally includes a quarter wave plate that is interposed between the optical combiner and at least one of the plurality of display modules or interposed between the optical combiner and at least one of the first and second catadioptric lenses.

[0147] In accordance with another embodiment, the display system optionally includes a high-angle rejection coating that is interposed between the optical combiner and at least one of the plurality of display modules or interposed between the optical combiner and at least one of the first and second catadioptric lenses.

[0148] In accordance with another embodiment, a display module of the plurality of display modules optionally includes an array of light-emitting diodes and an array of microlenses that overlaps the array of light-emitting diodes, the array of light-emitting diodes has a first horizontal pitch and a first vertical pitch, the array of microlenses has a second horizontal pitch and a second vertical pitch, the second vertical pitch is different than the first vertical pitch, and the second horizontal pitch is different than the first horizontal pitch.

[0149] In accordance with an embodiment, an electronic device includes a housing, a first waveguide coupled to the housing, a second waveguide coupled to the housing, a first chassis, a second chassis that is attached to the first chassis and the housing, a first lens that is interposed between the first chassis and the second chassis, a first portion of the first lens is adjacent to the first waveguide, a second lens that is interposed between the first chassis and the second chassis, where a first portion of the second lens is adjacent to the secondwaveguide, an optical combiner that is attached to the first chassis, and a plurality of display modules that is attached to the first chassis and that provide image light to the optical combiner.

[0150] In accordance with another embodiment, the housing optionally includes first and second housing structures, where the first and second chassis are interposed between the first and second housing structures, the housing optionally includes a mounting post that extends from the second housing structure towards the first housing structure, and the mounting post mates with an opening in the second chassis.

[0151] In accordance with another embodiment, the electronic device optionally includes an adhesive layer that attaches the mounting post to the second chassis within the opening.

[0152] In accordance with another embodiment, the first chassis optionally has a first portion that houses the optical combiner, where the first portion of the first chassis optionally has a plurality of openings, and the plurality of display modules optionally provides the image light to the optical combiner through the plurality of openings.

[0153] In accordance with another embodiment, the first chassis optionally has second and third portions, where the second chassis optionally has an upper surface that is attached to a lower surface of the second portion of the first chassis, the second chassis optionally has a lower surface that is attached to an upper surface of the third portion of the first chassis, the first and second lenses optionally have upper surfaces that are attached to the lower surface of the second portion of the first chassis, and the first and second lenses optionally have lower surfaces that are attached to the upper surface of the third portion of the first chassis.

[0154] In accordance with another embodiment, the electronic device optionally includes a flexible printed circuit with a plurality of bends, where the plurality of display modules is bonded to the flexible printed circuit.

[0155] In accordance with an embodiment, a display system includes a first waveguide, a second waveguide, a first catadioptric lens that is interposed between the first and second waveguides and that redirects image light to the first waveguide, a second catadioptric lens that is interposed between the first and second waveguides and that redirects the image light to the second waveguide, and at least one display module that provides the image light to the first and second catadioptric lenses, the at least one display module includes an array of lightemitting diodes and an array of microlenses that overlaps the array of light-emitting diodes, the array of light-emitting diodes has a first horizontal pitch and a first vertical pitch, and thearray of microlenses has a second horizontal pitch that is different than the first horizontal pitch and a second vertical pitch that is different than the first vertical pitch.

[0156] The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Claims

ClaimsWhat is Claimed is:

1. A display system comprising: a first waveguide; a second waveguide; an optical combiner that is interposed between the first and second waveguides; a first catadioptric lens that is interposed between the first and second waveguides and that redirects first image light from the optical combiner to the first waveguide; a second catadioptric lens that is interposed between the first and second waveguides and that redirects second image light from the optical combiner to the second waveguide; and a plurality of display modules that provides the first image light and the second image light to the optical combiner.

2. The display system defined in claim 1, wherein the plurality of display modules comprises three display modules that provide both the first image light and the second image light to the optical combiner.

3. The display system defined in claim 1, wherein the plurality of display modules comprises first, second, and third display modules that provide the first image light to the optical combiner and fourth, fifth, and sixth display modules that provide the second image light to the optical combiner.

4. The display system defined in claim 1, wherein the plurality of display modules comprises first and second active areas that share a first common backplane, third and fourth active areas that share a second common backplane, and fifth and sixth active areas that share a third common backplane.

5. The display system defined in claim 1, wherein the optical combinercomprises a surface with a first portion that is rougher than a second portion.

6. The display system defined in claim 5, wherein the surface is an exit surface of the optical combiner through which the first image light exits towards the first catadioptric lens and the second image light exits towards the second catadioptric lens.

7. The display system defined in claim 5, wherein the surface is an entrance surface of the optical combiner through which the first image light and the second image light enter the optical combiner from the plurality of display modules.

8. The display system defined in claim 1, further comprising: an ink coating on a surface of the optical combiner.

9. The display system defined in claim 1, wherein the optical combiner comprises at least one baffle.

10. The display system defined in claim 1, further comprising: a louver film that is interposed between the optical combiner and at least one of the plurality of display modules or interposed between the optical combiner and at least one of the first and second catadioptric lenses.

11. The display system defined in claim 1, further comprising: a linear polarizer that is interposed between the optical combiner and at least one of the plurality of display modules or interposed between the optical combiner and at least one of the first and second catadioptric lenses.

12. The display system defined in claim 1, further comprising: a quarter wave plate that is interposed between the optical combiner and at least one of the plurality of display modules or interposed between the optical combiner and at least one of the first and second catadioptric lenses.

13. The display system defined in claim 1, further comprising:a high-angle rejection coating that is interposed between the optical combiner and at least one of the plurality of display modules or interposed between the optical combiner and at least one of the first and second catadioptric lenses.

14. The display system defined in claim 1, wherein a display module of the plurality of display modules comprises an array of light-emitting diodes and an array of microlenses that overlaps the array of light-emitting diodes, wherein the array of lightemitting diodes has a first horizontal pitch and a first vertical pitch, wherein the array of microlenses has a second horizontal pitch and a second vertical pitch, wherein the second vertical pitch is different than the first vertical pitch, and wherein the second horizontal pitch is different than the first horizontal pitch.

15. An electronic device comprising: a housing; a first waveguide coupled to the housing; a second waveguide coupled to the housing; a first chassis; a second chassis that is attached to the first chassis and the housing; a first lens that is interposed between the first chassis and the second chassis, wherein a first portion of the first lens is adjacent to the first waveguide; a second lens that is interposed between the first chassis and the second chassis, wherein a first portion of the second lens is adjacent to the second waveguide; an optical combiner that is attached to the first chassis; and a plurality of display modules that is attached to the first chassis and that provide image light to the optical combiner.

16. The electronic device defined in claim 15, wherein the housing comprises first and second housing structures, wherein the first and second chassis are interposed between the first and second housing structures, wherein the housing comprises a mounting post that extends from the second housing structure towards the first housing structure, and wherein the mounting post mates with an opening in the second chassis.

17. The electronic device defined in claim 16, further comprising: an adhesive layer that attaches the mounting post to the second chassis within the opening.

18. The electronic device defined in claim 15, wherein the first chassis has a first portion that houses the optical combiner, wherein the first portion of the first chassis has a plurality of openings, and wherein the plurality of display modules provides the image light to the optical combiner through the plurality of openings.

19. The electronic device defined in claim 18, wherein the first chassis has second and third portions, wherein the second chassis has an upper surface that is attached to a lower surface of the second portion of the first chassis, wherein the second chassis has a lower surface that is attached to an upper surface of the third portion of the first chassis, wherein the first and second lenses have upper surfaces that are attached to the lower surface of the second portion of the first chassis, and wherein the first and second lenses have lower surfaces that are attached to the upper surface of the third portion of the first chassis.

20. The electronic device defined in claim 15, further comprising: a flexible printed circuit with a plurality of bends, wherein the plurality of display modules is bonded to the flexible printed circuit.

21. A display system comprising: a first waveguide; a second waveguide; a first catadioptric lens that is interposed between the first and second waveguides and that redirects image light to the first waveguide; a second catadioptric lens that is interposed between the first and second waveguides and that redirects the image light to the second waveguide; and at least one display module that provides the image light to the first and second catadioptric lenses, wherein the at least one display module comprises an array of light-emitting diodes and an array of microlenses that overlaps the array of light-emitting diodes, wherein the array of light-emitting diodes has a first horizontal pitch and a firstvertical pitch, and wherein the array of microlenses has a second horizontal pitch that is different than the first horizontal pitch and a second vertical pitch that is different than the first vertical pitch.

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